Cytomorphological Study of Medullary Carcinoma of Breast in Comparison to Infiltrating Ductal Carcinoma.

Introduction: Medullary breast carcinoma (MBC) is one of the rare variants of breast carcinoma, accounting for less than 5% of invasive breast carcinoma. MBCs relatively appear a decade earlier when compared to invasive ductal carcinoma (IDC NOS), which is more prevalent in the elderly age.

Subjects and Methods: A retrospective study was conducted in the Department of Pathology from 2009 to 2016. Fine needle aspiration cytology slides of MBCs and IDCs were retrieved, studied microscopically, and reviewed to compare the cytological features.

Results: During the study period, MBC cases were 12 and IDC were 319. Random 12 cases of IDC NOS were taken up for comparative cytological evaluation. Various cytological features are assessed and compared using chi square test and independent t test ratio. On comparison of IDC NOS and MBC cases in relation to the parameters like: syncytial clusters and nature of inflammatory infiltrate; the number of positive category was higher in MBC group (83.3%). In contrast, parameters like three-dimensional clusters, acinar pattern, and necrosis; the number of positive category was higher in IDC NOS group with a percentage of 91.7%, 100%, and 67%, respectively. Ratio of lymphoplasmacytic cells to tumor cells between the two showed that the ratio was higher in MBC group. This comparison was statistically significant with a P value of <0.001.

Conclusion: Though few variants of breast carcinoma contain lymphoplasmacytic infiltrate, the intensity and pattern of distribution of these lymphocytes and plasma cells in relation to tumor cells helps in distinguishing MBC from other breast carcinomas commonly IDC NOS on cytology. Also MBCs have a better prognosis when compared to IDC NOS.